The present invention relates to ice breaking vessels and, more particularly to a method and system for obtaining data indicative of forces experienced between the hull of a vessel and ice as the vessel passes through the ice so as to provide data for design purposes.
Vessels designed for ice breaking, e.g. Class A vessels with ice strengthened hulls, are primarily designed in accordance with theoretically posed criteria. Typically, for example, the structural design of the hull and the selection of a power plant are determined through theoretical calculations with some degree of tank testing of the resultant designs.
Actual conditions vary, of course, with regard to ice age, thickness, the extent of the ice field and other factors which are difficult to model theoretically and to reproduce in a tank environment. Moreover, although relatively accurate data may be gathered from tank testing of ice breaker designs, it is difficult to obtain the types of data which are helpful in ice breaker design even under controlled tank testing conditions.
For example, various methods have been devised to determine the stresses encountered on the hull of a vessel. A typical technique employed to monitor stresses involves the use of a strain gauge or a pressure transducer on the hull of the vessel. The use of strain gauges and pressure transducers provides very limited data as to the forces experienced on the hull of the vesel. Moreover, it is difficult to get accurate data from a strain gauge, particularly with respect to a localized area of the vessel's hull since forces applied at any one location are assumed by the numerous structural members within that area. Consequently, the stresses are transmitted throughout the localizd vicinity to surrounding structures, decreasing in intensity proportional to distance. Therefore, as simultaneous forces act upon the structure, an overlapping effect is derived which can lead to inaccurate assumptions.
It is accordingly an object of the present invention to provide a novel method and system for providing empirical data useful in the design of ice breaking vessels, whereby actual hull skin forces are measured avoiding the interrelationship of attendant structural members.
It is another object of the present invention to provide a novel method and system for providing empirical data related to frictional forces and thus frictional losses experienced on the hull of the vessel while it passes through ice.
It is yet another object of the present invention to provide a novel method and system for testing the ice breaking efficiency of a hull of a ship as the ship passes through ice wherein the measuring system does not protrude from the natural lines of vessel's hull.
It is a more specific object of the present invention to provide a method and system for testing the ice breaking efficiency of an ice-strengthened hull as the ship passes through ice derived by the measurement of frictional losses experienced on the hull in response to displacement of a movable member flush with the hull wherein the displacement is generally in the plane of the hull.
These and other objects and advantages are accomplished in accordance with the present invention as will become apparent to one skilled in the art to which the invention pertains from a perusal of the following detailed description when read in conjunction with the appended drawings.